Hi Pee: Here's some vocabulary to help you.
The 8040c is a frequency standard, not a GPSDO. That's to say it doesn't have a GPS receiver built in, but instead requires an external 1 PPS input.
It's very similar to the Stanford Research PRS-10 in that respect. http://www.prc68.com/I/PRS10.shtml The Thunderbolt is a combined GPS receiver and disciplined oscillator. http://www.prc68.com/I/ThunderBolt.shtml It's input is from a GPS antenna. Outputs are 1PPS and 10 MHz. The <1E-12 frequency accuracy after 20 minutes is not a specification, but rather a "performance parameter". That may be because it may depend on the quality of the 1 PPS input. Note the Allan deviation at 1 second is not as good. Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html Pee Akka wrote:
I'm currently doing my master's thesis on GPSDO devices. Nothing fancy but more than enough for a fledgling time-nutter. It seems that which ever direction I go with my master's, this place always pops up :) I'm a bit uncertain about how to interpret one of the GPSDO's specifications. The device in question is a a 8040c Rubidium Frequency Standard with a SA.22C-LN oscillator (ie. the low noise version). The specification states that its frequency accuracy (ie frequency offset) after 20 minutes of 1PPS GPS-disciplining is <1E-12. Do you think this specification the combined accuracy of the GPS receiver and 8040c device? In another words, if the 8040c is locked to GPS, is the whole receiver+8040c system's combined accuracy <1E-12? The GPS receiver that I have in use is XLi-GPS with +-30ns RMS 1PPS output. The datasheet for 8040c is here: http://www.symmetricom.com/resources/download-library/documents/datasheets/8040c/ The measurements that I've done indicate that at least the frequency stability (ADEV) of the 8040c is between 9E-13 and 1E-12 from 1s to 1000s. Thanks in advance. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
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